Fix N+1 query on signup bucket/requested_bucket in UserConProfileDrop

[nbudin]

Summary

After #11880 deployed, Sentry surfaced a new batch of N+1 issues (INTERCODE-186, 187, 189) with the offending query SELECT registration_policy_buckets.* WHERE id = $1 LIMIT $2, under AppRootLayoutQuery/CmsPageQuery. This is a genuinely different N+1 than the one #11880 fixed -- that one was a has_many collection load (registration_policy_buckets WHERE registration_policy_id = X); this one is belongs_to lookups (bucket/requested_bucket by their own id), so #11880's preload didn't cover it. It's likely this N+1 already existed since #11871 but was masked in Sentry's grouping by the much larger N+1 #11880 just fixed -- once that one went quiet, this one became the dominant signal.

Root cause

Traced it (by grepping actual CMS partial content in a production data dump) to a default/stock CMS partial pair present on most conventions' sites -- user_signups/user_signup (the "My Schedule" widget) and signup_bucket_description, which it renders per signup:

{%- elsif signup.bucket.name -%}
  ...
  {%- if signup.requested_bucket -%}

UserConProfileDrop#signups backs user_con_profile.signups for this widget. It already preloads several associations (event, run, rooms, team_members) but never picked up :bucket/:requested_bucket -- these only became real belongs_to associations in #11871 (previously bucket_key/requested_bucket_key were plain string columns needing no extra query at all), so the widget's preload list was never updated for them.

Fix

Added :bucket, :requested_bucket to UserConProfileDrop#signups's .includes(...). Added a regression test verified to fail without the fix (10 queries for 5 signups) and pass with it (2 total -- one batched query each for bucket and requested_bucket).

Also fixed a pre-existing (unrelated) Lint/MissingSuper rubocop offense on this same file's initialize, since the pre-commit hook rejects it once the file is touched at all.

Test plan

• test/liquid_drops/user_con_profile_drop_test.rb (new N+1 regression test + full existing suite)
• Full test/liquid_drops/ suite (39 tests)
• rubocop / stree clean

🤖 Generated with Claude Code